Tracked ultrasound vessel imaging

ABSTRACT

A medical imaging apparatus, such as including a processor circuit, can be used to construct a first image of a plane parallel to the surface of an ultrasonic imaging transducer, the plane corresponding to a locus at a specified depth within a first region of tissue. The apparatus can obtain information about a location of a vessel in the first image, then obtain, from a second region of tissue, imaging information corresponding to loci in planes parallel to the surface of the transducer, the planes at depths automatically determined at least in part using the obtained information about the location of the vessel in the first image. In an example, the apparatus can automatically determine an adjusted depth corresponding to the location of the vessel in the second region, and construct a second image of a plane corresponding to the adjusted depth within the tissue.

CLAIM OF PRIORITY

This patent application claims the benefit of priority, under 35 U.S.C.Section 119(e), to Hossack et al., U.S. Provisional Patent ApplicationSer. No. 61/266,784, entitled “Tracked C-scan Ultrasound Vessel ImagingSystem and Related Method,” filed on Dec. 4, 2009, which is herebyincorporated by reference herein in its entirety.

BACKGROUND

Ultrasound imaging can provide clinically-useful information tocaregivers. Such information can be used in real-time to assist invisualizing underlying anatomy during a variety of medical procedures.For example, without imaging, a needle insertion can generally involvepalpation of vessels in combination with reliance upon generalanatomical knowledge. Generally, a needle is to be inserted into a veinwithout accidentally penetrating any nearby pulsatile arteries.Commonly-accessed veins include the jugular vein, a subclavian vein, ora brachial vein, for example. Use of ultrasound imaging can reduce riskand can increase the confidence of the caregiver that the observedvessel is the intended target vessel, prior to needle insertion, ascompared to reliance on palpation or general anatomical knowledge.

OVERVIEW

The present inventors have recognized, among other things, that a C-scanultrasound imaging system can be used to assist in visualizing one ormore blood vessels, such as for use as a guidance tool for a needleinsertion procedure. The term “C-scan” generally refers to an ultrasoundimaging system configured to provide an image of a plane parallel to theface of an ultrasound transducer array (e.g., a matrix of transducersextending in two directions), such as including a target locus at aspecified depth or distance away from the face of the transducer array.In contrast, the term “B-scan” generally refers to an ultrasound imagingsystem configured to provide an image of a plane perpendicular to theface of an ultrasound transducer array (e.g., a linear array oftransducers).

Generally, a C-scan imaging system can be used to scan a range ofdepths, such as until the C-scan plane becomes centered in depth withrespect to a targeted vessel (e.g., a vein targeted for a needleinsertion). Then, to achieve high confidence that the scanned vessel isthe intended target vessel, the C-scan imaging system can be used toscan along the length of the vessel in the vicinity of the targetedneedle insertion site. Such depth searching can include scanning a rangeof depths, such as manually with the assistance of a user (e.g., acaregiver).

For example, such scanning can continue until a distinct vessel imagecan be observed in which the displayed cross-sectional width appears tobe maximized (e.g., corresponding to a plane approximately intersectingthe central axis of the vessel). The targeted vessel's depth withrespect to the skin surface will likely be non-uniform as the scanner ismoved around the surface of the skin, such as along the length of thevessel. Generally, the depth search can be repeated so as to continuallyor repetitively acquire a plane through the central axis of the intendedvessel. The present inventors have recognized, among other things, thatsuch a repetitive search for the vessel depth is a tedious task that canbe automated, or at least computer-assisted. The present subject matteris related to automated methods, apparatus, or computer program products(e.g., including a processor-readable medium) for determining anadjusted (e.g., corrected) C-scan depth.

A medical imaging apparatus, such as including a processor circuit, canbe used to construct a first image of a plane parallel to the surface ofan ultrasonic imaging transducer, the plane corresponding to a locus ata specified depth within a first region of tissue. The apparatus canobtain information about a location of a vessel in the first image, thenobtain, from a second region of tissue, imaging informationcorresponding to loci in planes parallel to the surface of thetransducer, the planes at depths automatically determined at least inpart using the obtained information about the location of the vessel inthe first image. In an example, the apparatus can automaticallydetermine an adjusted depth corresponding to the location of the vesselin the second region, and construct a second image of a planecorresponding to the adjusted depth within the tissue.

This overview is intended to provide an overview of subject matter ofthe present patent application. It is not intended to provide anexclusive or exhaustive explanation of the invention. The detaileddescription is included to provide further information about the presentpatent application.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 illustrates generally an example of an apparatus that can includean ultrasonic transducer array.

FIG. 2 illustrates generally an example of a vessel located below thesurface of an imaging subject's skin, the vessel including a depth thatvaries along a long axis of the vessel.

FIG. 3A-C illustrate generally illustrative examples of C-scanultrasound imaging information including a portion of a vessel, such asfor graphical presentation to a user, such as corresponding to a varietyof different scanned depths.

FIG. 4 illustrates generally an illustrative example of side-by-sideimaging information including both B-scan and C-scan ultrasound imaginginformation that can include a portion of a vessel, such as forgraphical presentation to a user.

FIGS. 5A-C illustrate generally an illustrative example that can includea repositionable or resizable indicator that can be manipulated by auser, such as to provide positional information about a vessel to anultrasound imaging apparatus, such as including information about adepth of a vessel.

FIGS. 6A-D illustrate generally illustrative examples of ultrasoundimaging information that can include C-scan ultrasound imaginginformation showing a boundary of a vessel, along with correspondingindicators of depth overlaid on B-scan ultrasound imaging informationincluding a cross-section of the vessel.

FIG. 7 illustrates generally an example of a technique that can includeconstructing an image of a region of tissue, such as using an adjusteddepth determined automatically by an ultrasound imaging apparatus.

FIGS. 8A-B illustrate generally an illustrative example of combiningimaging information from individual scans into a composite image.

DETAILED DESCRIPTION

FIG. 1 illustrates generally an example of an apparatus 100 that caninclude an ultrasonic transducer array 110. In an example, theultrasonic transducer array 110 can be placed in contact with a surface112 (e.g., skin) of a patient. The ultrasonic transducer array 110 canbe used such as to insonify a region of tissue below the surface 112,such as to assist in locating or visualizing a vessel 114. Such locationor visualization can be used to aid a caregiver in guiding a needle to atargeted vessel, such as prior to insertion of the needle.

In the example of FIG. 1, the transducer array 110 can be coupled tobeamforming circuitry or other processing circuitry, such as abeamformer 108. The beamformer 108 can be configured to amplify,phase-shift, time-gate, filter, or otherwise condition imaginginformation, such as provided to a processor circuit 102. For example,the receive path from each element in the transducer array 110 caninclude one or more of a low noise amplifier, a main-stage amplifier, aband-pass or a low-pass filter, or an analog to digital converter. In anexample, one or more signal conditioning steps can be performeddigitally, such as using the processor circuit 102. The term processoris used to generically refer to digital circuitry that can be used tomanipulate ultrasound imaging information. Such circuitry can includeone or more of a field-programmable gate array (FPGA) or otherprogrammable logic devices (PLDs), a microprocessor, a system-on-chipincluding one or more execution cores or other circuitry, amicrocontroller, or one or more or other circuits. In an example, theapparatus 100 of FIG. 1 can be configured to obtain imaging informationfrom loci corresponding to one or more planes parallel to the surface ofthe ultrasound transducer array 110 (e.g., to provide a “C-Scan”ultrasound image of loci in a plane parallel to the surface of thetransducer array 110 at a specified depth within the tissue 112), suchas shown in the example of FIG. 2.

In an example, the processor circuit 102 can be coupled to one or moreprocessor readable media 130, such as a memory circuit, a disk, or oneor more other memory technology or storage devices. In an example, acombination of one or more of the transducer array 110, the beamformer108, the processor circuit 102, processor-readable media 130, a display104, or a user input 106 can be included as a portion of a hand-heldultrasound imaging apparatus, such as including a two-dimensional arrayof ultrasound transducer elements. For example, such apparatus 100 caninclude apparatus or circuitry shown and described in Fuller, M. I.,Owen, K., Blalock, T. N., Hossack, J. A., and Walker, W. F., “Real timeimaging with the Sonic Window: A pocket-sized, C-scan, medicalultrasound device,” 2009 IEEE International Ultrasonics Symposium (IUS),September 2009, pp. 196-199, which is hereby incorporated by referenceherein in its entirety, including its discussion of a compact,integrated 60 element×60 element ultrasonic transducer array configuredto both insonify tissue and receive echo information from the tissue.

Other examples of apparatus or circuitry that can be included as aportion of the apparatus 100, or one or more techniques that can be usedin relation to the apparatus 100, can be found in one or more of Walker,W. F., et al., United States Patent Application PublicationUS2010/0268086, “Intuitive Ultrasonic Imaging System and Related MethodThereof,” or Walker, W. F., et al., United States Patent ApplicationPublication US2010/0063399, “Front End Circuitry for Imaging Systems andMethods of Use,” or Hossack, J. A., et al., United States PatentApplication Publication US2009/0048519, “Hybrid Dual Layer DiagnosticUltrasound Transducer Array” (issued as U.S. Pat. No. 7,750,537), orBlalock, T. N., et al., United States Patent Application Publication US2007/0016044, “Ultrasonic Transducer Drive,” or Blalock, T. N., et al.,United States Patent Application Publication US2007/0016022, “UltrasoundImaging Beam-Former Apparatus and Method,” or Hossack, J. A., et al.,United States Patent Application Publication US2006/0100516, “EfficientArchitecture for 3D and Planar Ultrasonic Imaging—Synthetic AxialAcquisition and Method thereof,” or Hossack, J. A., et al., UnitedStates Patent Application Publication US2006/0052697, “EfficientUltrasound System for Two-Dimensional C-scan Imaging and Related Methodthereof,” (issued as U.S. Pat. No. 7,402,136), or Walker, W. F., UnitedStates Patent Application Publication US2005/0154303, “IntuitiveUltrasonic Imaging System and Related Method thereof” (issued as U.S.Pat. No. 7,699,776), all of which are hereby incorporated by referenceherein in their respective entireties.

In an example, the processor circuit 102 (or one or more other processorcircuits) can be communicatively coupled to one or more of the userinput 106, or the display 104. For example, the user input 106 caninclude one or more of a keypad, a keyboard (e.g., located near or on aportion of ultrasound scanning assembly, or included as a portion of aworkstation configured to present or manipulate ultrasound imaginginformation), a mouse, a touch-screen control, a rotary control (e.g., aknob or rotary encoder), or a soft-key aligned with a portion of thedisplay 104, or including one or more other controls.

In an example, a system can include a first processor circuit 102, suchas configured to control one or more of the beamformer 108 or transducerarray 110. The system can include a second processor circuit, such asconfigured as an imaging post-processor, such as included as a portionof the workstation configured to present or manipulate ultrasoundimaging information. For example, the second processor circuit can beconfigured to obtain imaging information from the first processorcircuit 102 or from the one or more processor readable media 130 (or viaa wired or wireless network or other interface), such as to present theinformation to a user (e.g., a caregiver) via a display, or obtaininformation from the user via a user input.

In an example, the processor circuit 102 can be configured to constructone or more images (e.g., a set of two-dimensional or three-dimensionalrepresentations of the vessel 114), such as using imaging informationobtained using the ultrasonic transducer array 110. The processorcircuit 102 can present the constructed image to the user via thedisplay 104, such as presenting an image including one or more featuresor indicia as shown in the examples of FIG. 2, 3A-C, 4, 5A-C, 6A-D, 7,or 8A-B, below. The apparatus can generally include a two-dimensionalultrasonic imaging array since such an array can be compact andcost-effectively fabricated using solid state circuitry. However, othertechniques can include using a single transducer scanned in twodimensions or a one-dimensional array scanned in the array's elevationdimension, such as to provide imaging information similar to theinformation provided by a two-dimensional array.

FIG. 2 illustrates generally an example of a vessel 214, such as locatedbelow the surface of an imaging subject's skin 212, the vessel having adepth from the surface of the skin that can vary along a long axis ofthe vessel. In an example, a user (e.g., a caregiver) can use anultrasound imaging system to assist in locating or visualizing thevessel 214, such as using at least a portion of the apparatus shown inthe example of FIG. 1. Such location or visualization can help aid thecaregiver in inserting a needle into a desired target vessel. Generally,the needle is to be inserted into a vein without accidentallypenetrating any nearby pulsatile arteries. Commonly-accessed veinsinclude the jugular vein, a subclavian vein, or a brachial vein, forexample. In the example of FIG. 2, showing a simplified elevation view,an ultrasonic imaging transducer 210A can be placed in contact with theskin 212, such as in a first region. Ultrasonic imaging information canbe obtained, such as to provide (e.g., construct and present) a firstimage of the vessel 214. In an example, the image can be a C-scan (e.g.,C-mode) image of a plane corresponding to loci at a specified depth 220Abelow the skin 212 surface, the C-scan plane generally parallel to theface of the ultrasound imaging transducer 210A.

Generally, to obtain the first image of the vessel 214, the location ofthe imaging transducer 210A can be adjusted by the user, or otherwisemoved across the surface of the skin 212, such as to a location at ornear a desired needle insertion site. In an example, a user input can beused to vary the imaging depth until a long-axis vessel view is obtainedshowing the maximum observed distance between the opposite side walls ofthe targeted vessel 214 (e.g., as shown in the example of FIG. 3B). Inone approach, in a manually-tracking ultrasound imaging system, theultrasound imaging transducer 210A can then be moved to a second tissueregion 210B, laterally offset from the first region. In the secondregion, in such a manual approach, the depth of the C-scan imaging planemust be again manually adjusted by the user from a first specified depth220A, to a second specified depth 220B, such as to re-center the C-scanplane within the cross-section of the vessel 214, in the second tissueregion. Such manual adjustment can be tedious or time-consuming. Inanother example, a subsequent tissue region to be imaged can be offsetin depth from the first region (e.g., as the skin 212 is compressed),also resulting in a different depth of the vessel 214 relative to thetransducer, similar to the situation where the vessel depth varies alongits long axis.

The present inventors have recognized, among other things, that thesecond specified depth 220B, in the second region, can be automaticallydetermined, such as using the apparatus of FIG. 1 or one or moretechniques discussed in the examples below of FIG. 3A-C, 4, 5A-C, 6A-D,7, or 8A-B, such as including being guided by or using informationprovided by the user about the vessel 214 location in the first tissueregion. Thus, as the imaging transducer 210A is moved along the surfaceof the skin 212, the imaging apparatus can automatically track the depthof the vessel 214, such as moving a C-scan imaging plane automaticallyfrom the first depth 220A to a second depth 220B, or one or more otherlocations roughly following the path of the center of the long axis ofthe vessel.

FIG. 3A-C illustrate generally illustrative examples of C-scanultrasound imaging information that can include a portion of a vessel,such as for graphical presentation to a user, such as includingconstructed images 322A-C corresponding to a variety of differentscanned depths. As discussed above in the examples of FIGS. 1-2, thedepth of a C-scan imaging plane can be automatically adjusted, such asto track a depth of a targeted vessel using an external C-scanultrasound imaging transducer. Generally, ultrasonic imaginginformation, such as provided by the ultrasonic transducer array of FIG.1 can be converted into pixel brightness or color values, such as forpresentation on a display in two-dimensions.

In the examples of FIGS. 3A-C, an illustrative example of a presentationof C-scan imaging information can include images 322A-C of a bloodvessel 314A-C, such as surrounded by speckle in the region of adjacenttissue 312A-C, such as shown corresponding to planes imaged at variousdepths (e.g., 6 millimeters (mm), 8 mm, or 10 mm, respectively in FIGS.3A-C). Generally, the vessel 314A-C can appear blackened or relativelydarker (e.g., darker than surrounding tissue) in the constructed images322A-C, such as surrounded by enhanced borders (e.g., white, orrelatively lighter than the vessel interior or surrounding tissue),corresponding to reflection from the interface between the vessel 314A-Cwall and surrounding tissue 312A-C. In an example, a blood region of thevessel can include a contrast agent (e.g., DEFINITY®, available fromLantheus Medical Imaging, Inc., Billerica, Mass., U.S.A.). Such acontrast agent can be highly echogenic, such as causing an image of theblood portion of the vessel to appear white or brighter than surroundingtissue. The contrast agent can be administered just before or duringscanning, such as to enhance an appearance of one or more vessels to aidthe caregiver in locating the desired target vessel via ultrasoundimaging.

In an example, a user can provide information about the location of thevessel 314A-C, such as by adjusting a depth of the C-scan imaging plane,such as to obtain the view of FIG. 3B. For example, FIG. 3B image 322Bcan show a wider separation between the side walls of the vessel 314B ascompared to the shallower image 322A of FIG. 3A, or the deeper image322C of FIG. 3C.

In an example, the user can use an input, such as coupled to a processorcircuit and a display, as part of a graphical user interface (GUI), toprovide information about the location of the vessel 314B. In anexample, the user can provide information about one or more of a centerof the vessel 314B, or the location of one or more vessel walls. Suchinformation can be provided via adjusting or moving a graphicalindicator over a portion of the image 322B, such as including placing aline or cross-hair along one or more of the vessel walls or along acentral axis of the vessel. In an example, a user can indicate asequence of points or other loci, such as along one or more vessel wallsvisually identified from the image 322B.

The ultrasound imaging apparatus can then automatically vary the imagingdepth so as to provide a C-scan image 322B that can be roughly centeredwithin the vessel. As the transducer array is moved, such as laterallyalong the surface of the skin, the system can vary the image depth, suchas starting from the user-guided depth or using other vessel locationinformation provided by the user, such as to provide or adjust animaging depth to provide a C-scan image of the vessel that is roughlycentered in depth, within the vessel.

In an example, starting from an initial user-guided depth or using othervessel location information, the ultrasound imaging apparatus canautomatically scan a range of imaging depths, such as shallower ordeeper than the initial depth derived from the user-providedinformation. In an example, the depth can then be further adjusted(e.g., continuously, or at specified intervals of time, or upon requestof the user) as the transducer is moved, or as the relative location ofthe vessel changes with respect to the transducer (e.g., as the skin iscompressed, etc.).

Various techniques can be used to automatically determine the adjusteddepth (e.g., to “track” the vessel). For example, one technique forestimating the adjusted depth can include scanning tissue locicorresponding to one or more planes above and below the initial depth.Then, a mean or other central tendency of cross-sectional distancebetween the vessel 314A-C walls can be determined, such as assigning theadjusted depth to a depth corresponding to a maximum meancross-sectional distance (or using some other extremum or anothercentral tendency). In an example, a range of depths to be searched canbe determined at least in part using information about the vesseldiameter or width between the sidewalls, such as provided by the user.In an illustrative example, a 6 mm diameter vessel can use a range ofapproximately +/−3 mm (or some other range) to constrain the search forthe adjusted depth. For example, a warning (audible or visual) can begenerated if the center of the vessel cannot be automatically determinedwithin the specified search range.

In an example, one or more feature tracking techniques can be used suchas to automatically adjust the depth of the C-scan image, such as usinginformation about the location of one or more vessel 314A-C walls (orinformation about a change in the location of such vessel 314A-C walls).For example, pixel block matching can be used to determine motion of theone or more vessel 314A-C walls, such as including one or more of aMinimum Sum of Absolute Differences technique, a Maximum NormalizedCross Correlation technique, or a Minimized Sum of Squared Errorstechnique, such as to determine one or more of an X- or Y-offset in avessel 314A-C wall location (e.g., in successive scans, such as during adepth search). Generally, such methods are used for detecting a lateraloffset in an image plane (e.g., for use in forming a composite ofmultiple images), however, if the desired features to be tracked arerelatively simple or contrast from each other, such techniques mightstill be used. In an example, one or more motion estimates of one ormore features can be post-processed. For example, a motion estimate of afeature included in the imaging information can be low-pass filtered ormedian filtered, such as to reduce or minimize the impact of outliers ornoise.

For example, as the vessel wall separation increases or decreases (e.g.,as the C-scan imaging plane is automatically varied during a search forthe adjusted plane depth), such an increase or decrease can be used toprovide feedback. For example, if the vessel wall separation isdecreasing, the direction of the search (e.g., shallower or deeper) canbe reversed or otherwise adjusted.

While the term “pixel” is used, such feature tracking techniques neednot be restricted to operating on a (re)constructed C-scan image itself.For example, such techniques can include using one or more other formsof raw or intermediate ultrasound imaging data or information, such asbeamformed transducer information (e.g., RF data, such as delayed, orcomplex-sampled and phase-rotated), video information (e.g., videoB-mode information), a tissue harmonic signal arising from non-linearpropagation, Doppler information (e.g., velocity information), othermotion information obtained via non-Doppler techniques (e.g.,decorrelation analysis).

In an example, blood motion or velocity information can be used toassist in automatically determining the adjusted depth. For example, thecenter of the long axis of the vessel can correspond to a location whereblood motion is maximized, or where the velocity information indicates avelocity maximum (e.g., from the motion of blood through the vessel). Inan example, velocity information can be obtained using one or moretechniques or apparatus mentioned in Pang, et al., U.S. Pat. No.6,190,321, “Medical Diagnostic Ultrasound Imaging Methods for EstimatingMotion between Composite Ultrasonic Images and Recovering Color DopplerValues from Composite Images,” which is hereby incorporated by referenceherein in its entirety, including its disclosure of using Doppler-modeultrasonic techniques to extract velocity information, or Kasai, et al.,“Real-Time Two-Dimensional Blood Flow Imaging Using an AutocorrelationTechnique,” IEEE Transactions on Sonics and Ultrasonics, Vol. SU-32, No.3, May 1985, which is also hereby incorporated by reference herein inits entirety.

In an example, one or more indicators can be presented to indicate apresent or adjusted C-scan imaging depth, such as an alphanumericindicator, overlaying or otherwise comprising a portion of theconstructed image 322A-C, or a line aligned with or overlaying theconstructed image 322A-C. For example, in FIGS. 3A-C, a depth indicator324A-C can include a bar graph display, such as including a scale andone or more alphanumeric indicators, such as a filled or unfilled blockwithin rectangle whose height (or width, if rotated) is indicative of amaximum range of imaging depths. In an example, an indication can beprovided, such as audibly or via the display, to the user, such as inresponse to a deviation in estimated depth above a specified threshold(or outside a specified range), or when confidence in the estimator isbecoming unreliable, such as indicated by one or more “quality oftracking” metrics provided by a feature tracking or pixel block matchingtechnique of the examples discussed above.

In an example, such as during either an automatic determination of theadjusted depth, or in relation to construction of an image forpresentation to a user, one or more techniques can be used to suppressor remove noise or speckle. For example, noise or speckle (e.g., in thetissue 312A-C adjacent to the vessel 314A-C in images 322A-C) can besuppressed at least in part by low pass filtering, median filtering,anisotropic diffusion, or using one or more other techniques. In thecase of speckle in particular, spatial or frequency compounding can beused, in which de-correlated or independent speckle patterns can beaveraged. Generally, compounding can include using differentsub-apertures to obtain at least approximately independent specklepatterns or using imaging planes that can be slightly offset in depthfrom each other. In an illustrative example for C-scan imaging, specklepatterns can be obtained from successive acquisitions, such as at −1 mm,0 mm, and +1 mm with respect to the desired imaging plane (either fordisplay or depth search). In such an illustrative example, the specklepattern generally changes significantly while the underlying anatomyremains roughly static, allowing the speckle to be at least partiallysuppressed (e.g., by averaging).

FIG. 4 illustrates generally an illustrative example 400 of side-by-sideimaging information including both B-scan and C-scan ultrasound imaginginformation including a portion of a vessel, such as for graphicalpresentation to a user. While the examples of FIGS. 1, 2, and 3A-Cgenerally refer to C-scan imaging in a plane parallel to the transducerarray surface, it is possible to use such C-scan image information toconstruct a “synthetic” B-scan image corresponding to a desired planeperpendicular to the surface of the ultrasound transducer array. Forexample, in FIG. 4, a variety of depths can be automatically scanned,such as using the apparatus of FIG. 1, such as to construct a B-scanimage 424, including an elevation cross-sectional view of a vessel 414Asurrounded by tissue 412A. Various planes can cut through the B-scanview, such as a first plane 420A, corresponding to loci within tissue412A that can be shown longitudinally in the plan view of an adjacentC-scan image 422, showing tissue 412B and a long axis of the vessel414B. The separation between the vessel 414B walls in C-scan image cancorrespond to the distance between the vessel 414A walls in the plane420A. In an example, the user can provide a corrected depth to initiallyguide the search for a subsequent adjusted C-scan imaging depth, such asby moving an overlay on the synthetic B-scan image 424 indicative of theplane 420A to the location of the center of the vessel cross-section asshown in a plane 420B. Such an overlay, feature, or other indication caninclude a cross-hair, or one or more other indicia, such as discussedbelow in the examples of FIGS. 5A-C. In an example, the B-scan image 424can be displayed instead of the C-scan image 422, or the user can togglebetween the images, or both images can be displayed on a commonly-shareddisplay, etc., such as according to a user preference or the user input.

Synthetic B-scan information need not be used to construct an image forpresentation to the user. For example, synthetic B-scan imaginginformation (or other data or information corresponding to a planeperpendicular to the surface of the transducer array) can be used toprovide an adjusted C-scan imaging depth. For example, as discussedabove, pixel block matching, shape tracking, or other feature trackingcan be used to automatically identify the location of the center of theroughly circular cross-section of the vessel 414A as shown in thesynthetic B-scan image 424. In the case of a bifurcation of the vessel,such tracking can include attempting to track the larger-diameter vesselextending away from the bifurcation, or can include generating an alarmor other alert if the level of confidence in identifying the vesselcross-section falls below a specified threshold.

FIGS. 5A-C illustrate generally an illustrative example 500 that caninclude a repositionable or resizable indicator 520A that can bemanipulated by a user, such as to provide positional information about avessel 514A to an ultrasound imaging apparatus, such as includinginformation about a depth of a vessel. The images 524A-C can includesynthetic B-scan images provided to a user as a portion of a graphicaluser interface (GUI) to assist the user in identifying an initial depthof the vessel 514A. In the example of FIG. 5A, the indicator 520A isshown as a circle, but such an indicator need not be circular. Theindicator 520A can be repositioned to the center of the vessel 512A. InFIG. 5B, the indicator 520B can be resized, such as to provide theultrasonic imaging apparatus with an estimate of both the depth of thecenter of the vessel 514B, along with a diameter or separation betweenthe sidewalls at the center of the vessel 514B. In FIG. 5C, theindicator 514C, after adjustment by the user, can overlay the vessel514C.

FIGS. 6A-D illustrate generally illustrative examples of ultrasoundimaging information that can include C-scan ultrasound imaginginformation showing a boundary of a vessel, along with correspondingindicators of depth overlaid on B-scan ultrasound imaging informationincluding a cross-section of the vessel. As discussed in the examplesabove, a separation between sidewalls of the vessel can be used as oneparameter to aid in automatically determining an adjusted depth forC-scan imaging. FIGS. 6A-D illustrate generally another approach thatcan be used. In FIGS. 6A-D, a vessel 614A-D can include an interface(e.g., the vessel wall) between the tissue 614A-D and the vesselinterior that is highly reflective of ultrasonic energy. Such reflectioncan be almost specular, such as providing a highly enhanced (e.g.,white, or relatively lighter than the surrounding tissue) representationin a corresponding reconstructed image. Thus, in an example, a varietyof C-scan depths can be evaluated, such as to identify the top of thevessel (e.g., as shown in the plane of the vessel 614A of FIG. 6A), andthe bottom of the vessel (e.g., as shown in the plane of the vessel 614Cof FIG. 6C), such as using pixel block matching or feature trackingtechniques to identify highly enhanced ultrasonic signature of thevessel 614A-D wall. In an example, once the depth of the top of thevessel 614A and the bottom of the vessel 614C have been determined, amid-point (or other location) between the two depths can be used toestimate a depth of the center of the vessel (e.g., as shown in theplane of the vessel 614B in FIG. 6B). In FIG. 6D, a cross-section (e.g.,B-scan projection) view is shown to illustrate the locations of theplanes of the C-scan projections of FIGS. 6A-C with respect to thevessel 614D cross-section of FIG. 6D.

FIG. 7 illustrates generally an example of a technique 700 that caninclude constructing an image of a region of tissue, such as using anadjusted depth determined automatically by an ultrasound imagingapparatus. At 702, the technique 700 can include constructing a firstimage of a plane parallel to the surface of an ultrasonic transducerarray (e.g., a C-scan image), such as corresponding to a locus withinthe tissue at a specified depth from the transducer. At 704, thetechnique 700 can include obtaining information about a location of avessel in the first image, such as using one or more techniques orapparatus as discussed in the examples above. For example, the obtainingof information can include using information obtained from a user (e.g.,an initial vessel depth, a separation between sidewalls of the vessel,etc.), or the information can be determined automatically such as bysearching for a dark feature, a bright feature, or other informationindicative of a vessel.

At 706, the technique 700 can include obtaining, from a second region oftissue, imaging information corresponding to loci in planes parallel tothe surface of the transducer, the planes at depths automaticallydetermined at least in part using the obtained information about thelocation of the vessel in the first image. Such depths can include asearch performed by ultrasonic imaging apparatus to identify the depthof a center of a long axis of the vessel in the second tissue region,because the vessel depth can vary as the transducer is moved from alocation above the first region, to a location above the second region,along the skin. At 708, the technique 700 can include automaticallydetermining an adjusted depth corresponding to the location of thevessel in the second region. At 710, the technique 700 can includeconstructing a second image of a plane parallel to the surface of thetransducer, the plane corresponding to the adjusted depth within thetissue. In an example, the technique 700 can include using one or moreof the apparatus or techniques described in the examples above, such asto aid a user (e.g., a caregiver) in locating a target vessel amongstother vessels, for a needle insertion procedures, such as using anexternal C-scan ultrasonic imaging apparatus.

In an example, such as in relation to one or more of the apparatus ortechniques discussed above in FIG. 1, 2, 3A-C, 4, 5A-C, 6A-D, 7, or8A-B, the area of imaging information used for estimation ordetermination of the adjusted depth for successive C-scan images can beconstrained to a region within a specified absolute range of depths, orwithin a range of depths specified in relation to an initial specifieddepth. In an example (either involving C-scan, or B-scan information),the computation domain for feature tracking can be restricted to aspatial (or temporal) information corresponding to the region within ornearby the cross section of the vessel being targeted, such as to reducecomputation burden.

FIGS. 8A-B illustrate generally an illustrative example of combiningimaging information from individual scans into a composite image 824,such as in relation to one or more of the apparatus or techniquesdiscussed above in FIG. 1, 2, 3A-C, 4, 5A-C, 6A-D, or 7. One or moretechniques can be used to provide a composite or “mosaic” of multipleconstructed images, such as one or more images including informationfrom more than one tissue region. For example, in the illustrativeexample of FIG. 8A, C-scan imaging information can be obtained such ascorresponding to a field of view in a first location 822A, a secondlocation 822B, a third location 822C, a fourth location 822D, etc., as atransducer array is moved along the surface of a subject. One or moreportions of an underlying vessel 814A can be captured in the variousfields corresponding to the locations 822A-D, such as including anadjusted depth to provide imaging information centered with respect to acentral axis of the vessel 814A. Then, such as in the illustrativeexample 800 of FIG. 8B, a mosaic or combined image having an extendedfield of view can be constructed, such as including a rendering of avessel 814B, corresponding to imaged portions of the vessel 814A in oneor more of the locations 822A-D. Such a mosaic or composite can providea field of view that can be larger than the field of view provided by animage reconstructed from a single tissue region, such as imaged at asingle depth using a C-scan imaging mode.

For example, the apparatus of FIG. 1 can be used to continuously orperiodically update the adjusted depth of the vessel (e.g., tracking thedepth of the vessel), and either a two-dimensional or three-dimensionalrepresentation of the vessel can be presented. For example, speckle orpixel block matching techniques can be used to align and stitch segmentsor portions of the vessel from separate scans into a composite image,similar to the techniques discussed above with respect to featuretracking in the examples of FIGS. 3A-C. In an example, a lateral offsetbetween successive scan images (e.g., corresponding to different tissueregions) can be determined using such speckle or pixel block matchingtechniques. In an example, such pixel block matching or feature trackingtechniques can include one or more techniques mentioned in Weng, et.al., U.S. Pat. No. 5,575,286, “Method and apparatus for generating largecompound ultrasound image,” which is hereby incorporated herein byreference in its entirety, including its disclosure of techniques forpartitioning ultrasound information into pixel blocks and analyzing suchblocks in order to construct a compound image having an extended fieldof view.

A composite representation can generally be displayed as an elongatedvessel representation, visualized in either two or three dimensions. Inthe case of a two-dimensional representation, depth information canstill be presented such as using one or more indicia overlaying oraligned with the representation of the vessel, the one or more indiciaindicating a depth of the vessel at one or more locations correspondingto the one or more indicia. In an example, a color of the vessel atvarious loci along the representation of the vessel can be used toindicate the relative depth of the vessel in relation to the surface ofthe transducer, for vessel presentation in either two dimensions (e.g.,“flattened) or in a three-dimensional view. A color bar or “temperaturebar” can be provided, such as providing the user with a mapping betweena particular color and a particular depth.

In an example, a three-dimensional representation of a composite of theimaging information can be constructed such as using one or more featuretracking or motion estimation techniques mentioned in Hossack, et al.,U.S. Pat. No. 6,014,473, “Multiple Ultrasound Image Registration System,Method, and Transducer,” which is herein incorporated by reference inits entirety.

In an example, dynamic Doppler information from multiple scanned imagefields can be combined, such as to provide an extended field of viewthat can include both spatial and temporal extension, such as to provideinformation about dynamic (e.g., pulsatile flow) for presentation to theuser. Such a composite can be determined using apparatus or techniques,such as mentioned in Pang, et al., U.S. Pat. No. 6,558,325, “Medicaldiagnostic ultrasonic imaging method and system for displayingmulti-phase, multi-frame images,” which is hereby incorporated herein byreference in its entirety.

One or more techniques, such as mentioned in Pang '321, or Pang '325,can be used, such as to construct an image for presentation to a user,the image including one or more of gray C-scan information or “color”Doppler information (e.g., indicative of blood flow or other dynamicinformation). For example, Doppler or other motion information can beused to construct a colorized representation of motion within one ormore tracked blood vessels. Such color information can be coded orpresented according to a variety of techniques, such as displaying aportion of a vessel in color when motion or velocity informationcorresponding to the portion exceeds a specified threshold. In anexample, a range of colors can be mapped to motion or velocity, such asa scalar (e.g., unsigned) velocity or motion magnitude, or a vector(e.g., signed) representation (e.g., blood flow in one directionrepresented by a blue hue, blood flow in the opposite directionrepresented by a red hue, etc.).

In an example, apparatus or techniques such as discussed in the examplesabove can be used to construct a composite image or mosaic withoutrequiring that the depth of the vessel be automatically tracked. Forexample, the techniques discussed above can be generally applicable toconstructing a mosaic of C-scan imaging information, regardless ofwhether such information includes scans that have been automaticallydepth-adjusted.

In an example, such as in relation to one or more of the apparatus ortechniques discussed above in FIG. 1, 2, 3A-C, 4, 5A-C, 6A-D, 7, or8A-B, an audible or visual indicator or warning can be provided to theuser such as when one or more metrics indicative of the confidence ofthe adjusted depth exceed or drop below a specified threshold or violatea specified range. For example, during automatic tracking of vesseldepth, if an estimate of an adjusted depth for use in constructing animage deviates from a previous determination or deviates from theuser-supplied initial depth by more than a specified amount, a warningcan be displayed or an alarm can be sounded. In an example, a color orother overlay can be adjusted such as to indicate a loss of confidencein the depth estimate.

For example, one such “quality of estimate” metric can includedetermining a ratio or other relative indication of a minimum sum ofabsolute differences relative to a mean sum of absolute differences forall calculated sums during a particular depth estimation (or aggregatedacross multiple estimates). In this illustrative example, a lower ratioindicates a better estimate, and accordingly a threshold can bespecified above which an alarm or warning can be generated.

In an example, the initial depth estimate need not be provided by auser, but can be obtained automatically, such as using one or more ofthe apparatus or techniques discussed above in relation to automaticallyadjusting the depth of the scan. For example, an initial search can beperformed automatically, such as to determine a location of a dark areaor using the bright reflections of vessel walls to determine an initialdepth. In the case of synthetic B-scan image information, shape trackingor one or more other techniques can be used, such as to initiallyidentify a approximately circular cross section of a likely vesseltarget, including automatically determining one or more of a diameter ora central axis location of the vessel.

Various Examples and Notes

Example 1 can include, or can optionally be combined with subject matterof one or any combination of Examples 19-35 to include, subject matter(such as a method, a means for performing acts, or a machine-readablemedium including instructions that, when performed by the machine, canthe machine to perform acts) comprising constructing a first image of aplane parallel to the surface of an ultrasonic imaging transducer, theplane corresponding to a locus at a specified depth within a firstregion of tissue, using information obtained from the imagingtransducer, obtaining information about a location of a vessel in thefirst image, obtaining, from a second region of tissue, imaginginformation corresponding to loci in planes parallel to the surface ofthe transducer, the planes at depths automatically determined at leastin part using the obtained information about the location of the vesselin the first image, automatically determining an adjusted depthcorresponding to the location of the vessel in the second region, andconstructing a second image of a plane parallel to the surface of thetransducer, the plane corresponding to the adjusted depth within thetissue, the first and second regions offset from each other.

In Example 2, the subject matter of Example 1 can optionally includeconstructing the first image including insonifying the first region oftissue using the ultrasonic transducer array, and in response to theinsonification, obtaining echo information from the insonified firstregion of tissue, and obtaining imaging information from the secondregion of the tissue including insonifying the second region of tissueand obtain echo information from the insonified second region of tissue,the echo information corresponding to loci in planes parallel to thesurface of the transducer, the planes at depths automatically determinedat least in part using the obtained information about the location ofthe vessel in the first image.

In Example 3, the subject matter of one or more any combination ofExamples 1-2 can optionally include a specified depth corresponding tothe first image including information obtained via a user input.

In Example 4, the subject matter of one or more any combination ofExamples 1-3 can optionally include obtaining information about alocation of a vessel in the first image including obtaining informationabout one or more of a vessel center, or a location of the vessel walls,via a user input.

In Example 5, the subject matter of one or more any combination ofExamples 1-4 can optionally include information obtained via the userinput comprising one or more of a selection made via a keyboard, amouse, a rotary control input, a touch-screen input, or a soft-key inputlocated on or near a display.

In Example 6, the subject matter of one or more any combination ofExamples 1-5 can optionally include automatically determining anadjusted depth corresponding to the location of the vessel in the secondregion including determine a mean cross-sectional distance between thevessel walls corresponding to each of the scanned planes in the secondregion of tissue using an initial depth determined at least in partusing the information about the vessel location obtained via the userinput, estimating a depth corresponding to a maximum meancross-sectional distance using the determined mean cross-sectionaldistances, and assigning the estimated depth as the adjusted depth.

In Example 7, the subject matter of one or more any combination ofExamples 1-6 can optionally include automatically determining anadjusted depth corresponding to the location of the vessel in the secondregion including determining a first depth using obtained imaginginformation indicative of a shallow boundary of the vessel, closer tothe imaging transducer in depth than a deep boundary of the vessel,determining a second depth indicative of the deep boundary of thevessel, estimating a depth corresponding to the center of the long axisof the vessel between the shallow and deep boundaries, assigning theestimated depth as the adjusted depth, and one or more of thedetermining the first depth or determining the second depth includingusing information about the vessel location obtained via the user input.

In Example 8, the subject matter of one or more any combination ofExamples 1-7 can optionally include determining the depths of one ormore of the shallow or deep boundaries of the vessel includingiteratively obtaining imaging information, and constructing images,corresponding to a variety of depths, until a bright reflectioncorresponding to an interface between the vessel and the surroundingtissue is detected.

In Example 9, the subject matter of one or more any combination ofExamples 1-8 can optionally include declare an error if no brightreflection corresponding to an interface between the vessel and thesurrounding tissue can be detected.

In Example 10, the subject matter of one or more any combination ofExamples 1-9 can optionally include automatically determining anadjusted depth corresponding to the location of the vessel in the secondregion including obtaining imaging information including blood motioninformation, estimating a depth corresponding to the center of the longaxis of the vessel where the blood motion information indicates amaximum blood motion, assigning the estimated depth as the adjusteddepth, the estimating a depth corresponding to the center of the longaxis of the vessel, including using information about the vessellocation obtained via the user input.

In Example 11, the subject matter of one or more any combination ofExamples 1-10 can optionally include presenting the constructed secondimage via a display.

In Example 12, the subject matter of one or more any combination ofExamples 1-11 can optionally include displaying an indicator of theadjusted depth on or near the constructed second image via the display,the indicator including one or more of a bar-graph, an alphanumericindicator, a color overlaying or otherwise comprising a portion of theconstructed second image, or a line aligned with or overlaying theconstructed second image.

In Example 13, the subject matter of one or more any combination ofExamples 1-12 can optionally include obtaining imaging informationincluding blood motion information, constructing a composite imageincluding the vessel and a representation of blood motion correspondingto at least a portion of the vessel, and presenting the constructedimage via the display.

In Example 14, the subject matter of one or more any combination ofExamples 1-13 can optionally include constructing a third image of aplane perpendicular to the surface of the imaging transducer, the thirdimage including a cross-sectional view of the vessel, the third imagedetermined using information about a series of constructed imagescorresponding various depths of planes parallel to the surface of theimaging transducer.

In Example 15, the subject matter of one or more any combination ofExamples 1-14 can optionally include constructing a composite imageincluding the first and second constructed images.

In Example 16, the subject matter of one or more any combination ofExamples 1-15 can optionally include constructing a composite imageincluding constructing a three-dimensional representation of the vessel.

In Example 17, the subject matter of one or more any combination ofExamples 1-16 can optionally include constructing a composite imageincluding constructing a two-dimensional representation of the vessel,including one or more indicia overlaying or aligned with therepresentation of the vessel, the one or more indicia indicating a depthof the vessel at one or more locations corresponding to the one or moreindicia.

In Example 18, the subject matter of one or more any combination ofExamples 1-17 can optionally include first and second regions that canat least partially overlap with each other.

Example 19 includes subject matter (such as an apparatus) comprising anultrasonic imaging transducer configured to obtain imaging informationfrom tissue, and a processor circuit coupled to the imaging transducerand configured to construct a first image of a plane parallel to thesurface of the imaging transducer, the plane corresponding to a locus ata specified depth within a first region of tissue, using informationobtained from the imaging transducer, obtain information about alocation of a vessel in the first image, obtain, from a second region oftissue, imaging information corresponding to loci in planes parallel tothe surface of the transducer, the planes at depths automaticallydetermined at least in part using the obtained information about thelocation of the vessel in the first image, automatically determine anadjusted depth corresponding to the location of the vessel in the secondregion, and construct a second image of a plane parallel to the surfaceof the imaging transducer, the plane corresponding to the adjusted depthwithin the tissue, the first and second regions offset from each other.

In Example 20, the subject matter of Example 19 can optionally includean ultrasonic transducer array located externally to the tissue, theprocessor circuit configured to construct the first image configured tocontrol the ultrasonic transducer array to insonify the first region oftissue using the ultrasonic transducer array, and in response toinsonification, obtain echo information from the insonified first regionof tissue, and the processor circuit configured to obtain imaginginformation from the second region of tissue configured to control theultrasonic transducer array to insonify the second region of tissue andobtain echo information from the insonified second region of tissue, theecho information corresponding to loci in planes parallel to the surfaceof the transducer, the planes at depths automatically determined atleast in part using the received information about the location of thevessel in the first image.

In Example 21, the subject matter of one or more any combination ofExamples 19-20 can optionally include a user input, and the specifieddepth corresponding to the first image includes information obtained bythe user input.

In Example 22, the subject matter of one or more any combination ofExamples 19-21 can optionally include a user input, the informationabout the location of the vessel image includes information obtained bythe user input about one or more of a vessel center, or a location ofthe vessel walls.

In Example 23, the subject matter of one or more any combination ofExamples 19-22 can optionally include a user input comprising one ormore of a keyboard, a mouse, a rotary control input, a touch-screeninput, or a soft-key input located on or near a display.

In Example 24, the subject matter of one or more any combination ofExamples 19-23 can optionally include a processor circuit configured toautomatically determine an adjusted depth, the processor circuitconfigured to determine a mean cross-sectional distance between thevessel walls corresponding to each of the scanned planes in the secondregion of tissue using an initial depth determined at least in partusing the information about the vessel location obtained using the userinput, estimate a depth corresponding to a maximum mean cross-sectionaldistance using the determined mean cross-sectional distances, and assignthe estimated depth as the adjusted depth.

In Example 25, the subject matter of one or more any combination ofExamples 19-24 can optionally include a processor circuit configured toautomatically determine an adjusted depth, the processor circuitconfigured to determine a first depth using obtained imaging informationindicative of a shallow boundary of the vessel, closer to the imagingtransducer in depth than a deep boundary of the vessel, determine asecond depth indicative of the deep boundary of the vessel, estimate adepth corresponding to the center of the long axis of the vessel betweenthe shallow and deep boundaries, and assign the estimated depth as theadjusted depth, the one or more of the determining the first depth ordetermining the second depth includes using information about the vessellocation obtained via the user input.

In Example 26, the subject matter of one or more any combination ofExamples 19-25 can optionally include a processor circuit configured toobtain imaging information including blood motion information, estimatea depth corresponding to the center of the long axis of the vessel wherethe blood motion information indicates a maximum blood motion, andassign the estimated depth as the adjusted depth, the estimating a depthcorresponding to the center of the long axis of the vessel includesusing information about the vessel location obtained using the userinput.

In Example 27, the subject matter of one or more any combination ofExamples 19-26 can optionally include a display coupled to the processorcircuit, and the processor circuit is configured to present theconstructed second image using the display.

In Example 28, the subject matter of one or more any combination ofExamples 19-27 can optionally include a processor circuit configured topresent an indicator of the adjusted depth on or near the constructedsecond image using the display, the indicator including one or more of abar-graph, an alphanumeric indicator, a color overlaying or otherwisecomprising a portion of the constructed second image, or a line alignedwith or overlaying the constructed second image.

In Example 29, the subject matter of one or more any combination ofExamples 19-28 can optionally include a processor circuit configured toobtain imaging information including blood motion information, constructa composite image including the vessel and a representation of bloodmotion corresponding to at least a portion of the vessel, and presentthe constructed image via the display.

In Example 30, the subject matter of one or more any combination ofExamples 19-29 can optionally include a processor circuit is configuredto construct a third image of a plane perpendicular to the surface ofthe imaging transducer, the third image including a cross-sectional viewof the vessel, the third image determined using information about aseries of constructed images corresponding various depths of planesparallel to the imaging transducer, and present the third image usingthe display.

In Example 31, the subject matter of one or more any combination ofExamples 19-30 can optionally include a processor circuit configured toconstruct a composite image including the first and second constructedimages, and present the composite image using the display.

In Example 32, the subject matter of one or more any combination ofExamples 19-31 can optionally include a processor circuit configured toconstruct a three-dimensional representation of the vessel, and topresent the three-dimensional representation of the vessel using thedisplay.

In Example 33, the subject matter of one or more any combination ofExamples 19-32 can optionally include a processor circuit configured toconstruct a two-dimensional representation of the vessel and present thetwo-dimensional representation of the vessel using the display, thepresentation including one or more indicia overlaying or aligned withthe representation of the vessel, the one or more indicia indicating adepth of the vessel at one or more locations corresponding to the one ormore indicia.

In Example 34, the subject matter of one or more any combination ofExamples 19-33 can optionally include first and second regions that canat least partially overlap with each other.

Example 35 includes subject matter (such as an apparatus) comprising auser input, a display, an ultrasonic imaging transducer configured toobtain imaging information from tissue, and a processor circuit coupledto the ultrasonic transducer array and configured to construct a firstimage of a plane parallel to the surface of the imaging transducer, theplane corresponding to a locus at a specified depth within the firstregion of tissue, using information obtained from the imagingtransducer, present the constructed first image using the display,obtain information about a location of a vessel in the first image usingthe user input, obtain, from a second region of tissue, imaginginformation corresponding to loci in planes parallel to the surface ofthe transducer, the planes at depths automatically determined at leastin part using the obtained information about the location of the vesselin the first image, automatically determine an adjusted depthcorresponding to the location of the vessel in the second image,construct a second image of a plane parallel to the surface of theimaging transducer, the plane corresponding to the adjusted depth withinthe tissue, and present the constructed second image using the display,the first and second regions offset from each other.

In Example 36, the subject matter of one or more any combination ofExamples 19-35 can optionally include an imaging transducer comprisingan ultrasonic transducer array located externally to the tissue, theprocessor circuit configured to construct the first image is configuredto control the ultrasonic transducer array to insonify the first regionof tissue using the ultrasonic transducer array, and in response toinsonification, obtain echo information from the insonified first regionof tissue, and the processor circuit configured to obtain imaginginformation from the second region of tissue, the processor circuitconfigured to control the ultrasonic transducer array to insonify thesecond region of tissue and obtain echo information from the insonifiedsecond region of tissue, the echo information corresponding to loci inplanes parallel to the surface of the transducer, the planes at depthsautomatically determined at least in part using the received informationabout the location of the vessel in the first image.

These non-limiting examples can be combined in any permutation orcombination.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

All publications, patents, and patent documents referred to in thisdocument are incorporated by reference herein in their entirety, asthough individually incorporated by reference. In the event ofinconsistent usages between this document and those documents soincorporated by reference, the usage in the incorporated reference(s)should be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, or process that includes elements in addition to those listedafter such a term in a claim are still deemed to fall within the scopeof that claim. Moreover, in the following claims, the terms “first,”“second,” and “third,” etc. are used merely as labels, and are notintended to impose numerical requirements on their objects.

Method examples described herein can be machine or computer-implementedat least in part. Some examples can include a computer-readable mediumor machine-readable medium encoded with instructions operable toconfigure an electronic device to perform methods as described in theabove examples. An implementation of such methods can include code, suchas microcode, assembly language code, a higher-level language code, orthe like. Such code can include computer readable instructions forperforming various methods. The code may form portions of computerprogram products. Further, in an example, the code can be tangiblystored on one or more volatile, non-transitory, or non-volatile tangiblecomputer-readable media, such as during execution or at other times.Examples of these tangible computer-readable media can include, but arenot limited to, hard disks, removable magnetic disks, removable opticaldisks (e.g., compact disks and digital video disks), magnetic cassettes,memory cards or sticks, random access memories (RAMs), read onlymemories (ROMs), and the like.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment, and it is contemplated that such embodiments can be combinedwith each other in various combinations or permutations. The scope ofthe invention should be determined with reference to the appendedclaims, along with the full scope of equivalents to which such claimsare entitled.

1. A processor-readable medium comprising instructions that, whenperformed by the processor, cause the processor to: construct a firstimage of a plane parallel to the surface of an ultrasonic imagingtransducer, the plane corresponding to a locus at a specified depthwithin a first region of tissue, using information obtained from theimaging transducer; obtain information about a location of a vessel inthe first image; obtain, from a second region of tissue, imaginginformation corresponding to loci in planes parallel to the surface ofthe transducer, the planes at depths automatically determined at leastin part using the obtained information about the location of the vesselin the first image; automatically determine an adjusted depthcorresponding to the location of the vessel in the second region; andconstruct a second image of a plane parallel to the surface of thetransducer, the plane corresponding to the adjusted depth within thetissue; and wherein the first and second regions are offset from eachother.
 2. The processor-readable medium of claim 1, wherein the imagingtransducer comprises an ultrasonic transducer array located externallyto the tissue; wherein the instructions to construct the first imagecomprise instructions that cause the processor to: insonify the firstregion of tissue using the ultrasonic transducer array; and in responseto the insonification, obtain echo information from the insonified firstregion of tissue; and wherein the instructions to obtain imaginginformation from the second region of the tissue include instructionsthat cause the processor to: insonify the second region of tissue andobtain echo information from the insonified second region of tissue, theecho information corresponding to loci in planes parallel to the surfaceof the transducer, the planes at depths automatically determined atleast in part using the obtained information about the location of thevessel in the first image.
 3. The processor-readable medium of claim 1,wherein the specified depth corresponding to the first image includesinformation obtained via a user input.
 4. The processor-readable mediumof claim 1, wherein the instructions that cause the processor to obtaininformation about a location of a vessel in the first image includeinstructions that cause the processor to obtain information about one ormore of a vessel center, or a location of the vessel walls, via a userinput.
 5. The processor-readable medium of claim 4, wherein theinformation obtained via the user input includes one or more of aselection made via a keyboard, a mouse, a rotary control input, atouch-screen input, or a soft-key input located on or near a display. 6.The processor-readable medium of claim 4, wherein the instructions toautomatically determine an adjusted depth corresponding to the locationof the vessel in the second region include instructions to: determine amean cross-sectional distance between the vessel walls corresponding toeach of the scanned planes in the second region of tissue using aninitial depth determined at least in part using the information aboutthe vessel location obtained via the user input; estimate a depthcorresponding to a maximum mean cross-sectional distance using thedetermined mean cross-sectional distances; and assign the estimateddepth as the adjusted depth.
 7. The processor-readable medium of claim4, wherein the instructions to automatically determine an adjusted depthcorresponding to the location of the vessel in the second region includeinstructions to: determine a first depth using obtained imaginginformation indicative of a shallow boundary of the vessel, closer tothe imaging transducer in depth than a deep boundary of the vessel;determine a second depth indicative of the deep boundary of the vessel;estimate a depth corresponding to the center of the long axis of thevessel between the shallow and deep boundaries; and assign the estimateddepth as the adjusted depth; and wherein one or more of the determiningthe first depth or determining the second depth includes usinginformation about the vessel location obtained via the user input. 8.The processor-readable medium of claim 7, wherein the instructions todetermine the depths of one or more of the shallow or deep boundaries ofthe vessel include instructions to iteratively obtain imaginginformation, and construct images, corresponding to a variety of depths,until a bright reflection corresponding to an interface between thevessel and the surrounding tissue is detected.
 9. The processor-readablemedium of claim 8, wherein the instruction comprise instructions thatcause the processor to declare an error if no bright reflectioncorresponding to an interface between the vessel and the surroundingtissue can be detected.
 10. The processor readable medium of claim 4,wherein the instructions to automatically determine an adjusted depthcorresponding to the location of the vessel in the second region includeinstructions to obtain imaging information including blood motioninformation; estimate a depth corresponding to the center of the longaxis of the vessel where the blood motion information indicates amaximum blood motion; and assign the estimated depth as the adjusteddepth; and wherein the estimating a depth corresponding to the center ofthe long axis of the vessel includes using information about the vessellocation obtained via the user input.
 11. The processor-readable mediumof claim 1, wherein the instructions comprise instructions that causethe processor to present the constructed second image via a display. 12.The processor-readable medium of claim 11, wherein the instructionscomprise instructions that cause the processor to display an indicatorof the adjusted depth on or near the constructed second image via thedisplay, the indicator including one or more of a bar-graph, analphanumeric indicator, a color overlaying or otherwise comprising aportion of the constructed second image, or a line aligned with oroverlaying the constructed second image.
 13. The processor-readablemedium of claim 11, wherein the instructions comprise instructions thatcause the processor to: obtain imaging information including bloodmotion information; construct a composite image including the vessel anda representation of blood motion corresponding to at least a portion ofthe vessel; and present the constructed image via the display.
 14. Theprocessor-readable medium of claim 11, wherein the instructions compriseinstructions to construct a third image of a plane perpendicular to thesurface of the imaging transducer, the third image including across-sectional view of the vessel, the third image determined usinginformation about a series of constructed images corresponding variousdepths of planes parallel to the surface of the imaging transducer. 15.The processor-readable medium of claim 1, wherein the instructionscomprise instructions to construct a composite image including the firstand second constructed images.
 16. The processor-readable medium ofclaim 15, wherein the instructions to construct the composite imageinclude instructions to construct a three-dimensional representation ofthe vessel.
 17. The processor-readable medium of claim 15, wherein theinstructions to construct the composite image include instructions toconstruct a two-dimensional representation of the vessel, including oneor more indicia overlaying or aligned with the representation of thevessel, the one or more indicia indicating a depth of the vessel at oneor more locations corresponding to the one or more indicia.
 18. Theprocessor-readable medium of claim 1, wherein the first and secondregions at least partially overlap with each other.
 19. A system,comprising: an ultrasonic imaging transducer configured to obtainimaging information from tissue; and a processor circuit coupled to theimaging transducer and configured to: construct a first image of a planeparallel to the surface of the imaging transducer, the planecorresponding to a locus at a specified depth within a first region oftissue, using information obtained from the imaging transducer; obtaininformation about a location of a vessel in the first image; obtain,from a second region of tissue, imaging information corresponding toloci in planes parallel to the surface of the transducer, the planes atdepths automatically determined at least in part using the obtainedinformation about the location of the vessel in the first image;automatically determine an adjusted depth corresponding to the locationof the vessel in the second region; and construct a second image of aplane parallel to the surface of the imaging transducer, the planecorresponding to the adjusted depth within the tissue; and wherein thefirst and second regions are offset from each other.
 20. The system ofclaim 19, wherein the imaging transducer comprises an ultrasonictransducer array located externally to the tissue; wherein the processorcircuit configured to construct the first image is configured to:control the ultrasonic transducer array to insonify the first region oftissue using the ultrasonic transducer array; and in response toinsonification, obtain echo information from the insonified first regionof tissue; and wherein the processor circuit configured to obtainimaging information from the second region of tissue is configured to:control the ultrasonic transducer array to insonify the second region oftissue and obtain echo information from the insonified second region oftissue, the echo information corresponding to loci in planes parallel tothe surface of the transducer, the planes at depths automaticallydetermined at least in part using the received information about thelocation of the vessel in the first image.
 21. The system of claim 19,comprising a user input; and wherein the specified depth correspondingto the first image includes information obtained by the user input. 22.The system of claim 19, comprising a user input; and wherein theinformation about the location of the vessel image includes informationobtained by the user input about one or more of a vessel center, or alocation of the vessel walls.
 23. The system of claim 22, wherein theuser input comprises one or more of a keyboard, a mouse, a rotarycontrol input, a touch-screen input, or a soft-key input located on ornear a display.
 24. The system of claim 22, wherein the processorcircuit configured to automatically determine an adjusted depth isconfigured to: determine a mean cross-sectional distance between thevessel walls corresponding to each of the scanned planes in the secondregion of tissue using an initial depth determined at least in partusing the information about the vessel location obtained using the userinput; estimate a depth corresponding to a maximum mean cross-sectionaldistance using the determined mean cross-sectional distances; and assignthe estimated depth as the adjusted depth.
 25. The system of claim 22,wherein the processor circuit configured to automatically determine anadjusted depth is configured to: determine a first depth using obtainedimaging information indicative of a shallow boundary of the vessel,closer to the imaging transducer in depth than a deep boundary of thevessel; determine a second depth indicative of the deep boundary of thevessel; estimate a depth corresponding to the center of the long axis ofthe vessel between the shallow and deep boundaries; and assign theestimated depth as the adjusted depth; and wherein one or more of thedetermining the first depth or determining the second depth includesusing information about the vessel location obtained via the user input.26. The system of claim 22, wherein the processor circuit is configuredto obtain imaging information including blood motion information;estimate a depth corresponding to the center of the long axis of thevessel where the blood motion information indicates a maximum bloodmotion; and assign the estimated depth as the adjusted depth; andwherein the estimating a depth corresponding to the center of the longaxis of the vessel includes using information about the vessel locationobtained using the user input.
 27. The system of claim 18, comprising adisplay coupled to the processor circuit; and wherein the processorcircuit is configured to present the constructed second image using thedisplay.
 28. The system of claim 27, wherein the processor circuit isconfigured to present an indicator of the adjusted depth on or near theconstructed second image using the display, the indicator including oneor more of a bar-graph, an alphanumeric indicator, a color overlaying orotherwise comprising a portion of the constructed second image, or aline aligned with or overlaying the constructed second image.
 29. Thesystem of claim 27, wherein the processor circuit is configured to:obtain imaging information including blood motion information; constructa composite image including the vessel and a representation of bloodmotion corresponding to at least a portion of the vessel; and presentthe constructed image via the display.
 30. The system of claim 27,wherein the processor circuit is configured to: construct a third imageof a plane perpendicular to the surface of the imaging transducer, thethird image including a cross-sectional view of the vessel, the thirdimage determined using information about a series of constructed imagescorresponding various depths of planes parallel to the imagingtransducer; and present the third image using the display.
 31. Thesystem of claim 19, wherein the processor circuit is configured to:construct a composite image including the first and second constructedimages; and present the composite image using the display.
 32. Thesystem of claim 31, wherein the processor circuit configured toconstruct the composite image is configured to: construct athree-dimensional representation of the vessel; and present thethree-dimensional representation of the vessel using the display. 33.The system of claim 31, wherein the processor circuit configured toconstruct the composite image is configured to: construct atwo-dimensional representation of the vessel; and present thetwo-dimensional representation of the vessel using the display, thepresentation including one or more indicia overlaying or aligned withthe representation of the vessel, the one or more indicia indicating adepth of the vessel at one or more locations corresponding to the one ormore indicia.
 34. The system of claim 19, wherein the first and secondregions at least partially overlap with each other.
 35. A system,comprising: a user input; a display; an ultrasonic imaging transducerconfigured to obtain imaging information from tissue; and a processorcircuit coupled to the ultrasonic transducer array and configured to:construct a first image of a plane parallel to the surface of theimaging transducer, the plane corresponding to a locus at a specifieddepth within the first region of tissue, using information obtained fromthe imaging transducer; present the constructed first image using thedisplay; obtain information about a location of a vessel in the firstimage using the user input; obtain, from a second region of tissue,imaging information corresponding to loci in planes parallel to thesurface of the transducer, the planes at depths automatically determinedat least in part using the obtained information about the location ofthe vessel in the first image; automatically determine an adjusted depthcorresponding to the location of the vessel in the second image;construct a second image of a plane parallel to the surface of theimaging transducer, the plane corresponding to the adjusted depth withinthe tissue; and present the constructed second image using the display;and wherein the first and second regions are offset from each other. 36.The system of claim 35, wherein the imaging transducer comprises anultrasonic transducer array located externally to the tissue; whereinthe processor circuit configured to construct the first image isconfigured to: control the ultrasonic transducer array to insonify thefirst region of tissue using the ultrasonic transducer array; inresponse to insonification, obtain echo information from the insonifiedfirst region of tissue; and wherein the processor circuit configured toobtain imaging information from the second region of tissue isconfigured to: control the ultrasonic transducer array to insonify thesecond region of tissue and obtain echo information from the insonifiedsecond region of tissue, the echo information corresponding to loci inplanes parallel to the surface of the transducer, the planes at depthsautomatically determined at least in part using the received informationabout the location of the vessel in the first image.